The Federal Emergency Management Agency (FEMA), a part of the US Department of Homeland Security, has calculated the risk factors of every American county for 18 types of natural disasters. The index includes earthquakes, hurricanes, tornadoes, floods and volcanoes besides tsunamis. As per the report, Los Angeles is the riskiest place on the National Risk Index.

FEMA's calculation revealed that eastern cities such as Philadelphia and New York rank far higher on the risk for tornadoes than tornado-prone regions like Oklahoma and Kansas, while one county in Washington state is found to have the biggest coastal flood risk.

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Riskiest US counties

National Risk Index

The index scores the counties on how often natural disasters strike, how many people and property face destruction, how vulnerable the county population is socially and how well the affected region can overcome. All of that results in a high-risk assessment for big US cities with both poor population and expensive property that are ill-prepared for once-in-a-generation natural catastrophe. Mike Grimm, the current Acting Deputy Associate Administrator of FEMA, said that the degree of the risk is not only about how often a type of natural disaster strikes a region on the American soil, but how bad the toll would be.

In terms of the tornado, two New York City counties, Philadelphia, St. Louis and Hudson County (New Jersey) are the top five riskiest places according to the agency. Oklahoma county, which witnessed over 120 tornadoes since 1950, including the one which killed 36 people in 1999, ranks 120th on the list.

Much of the FEMA calculations are based on the work of Susan Cutter, the Director of the Hazards & Vulnerability Research Institute at the University of South Carolina. According to the expert, a tornado in the top five counties would be of low frequency but the consequence would be higher due to a lot of property exposure in the region. "Therefore, a small tornado can create a large dollar loss," she added.

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Natural disaster

Grimm said people living in New York are far less aware of the risk of such environmental disasters and are less prepared. According to National Weather Service, last year, many cities, mostly on the East Coast, had witnessed more tornadoes than Kansas' Wichita. Even though Oklahoma is twice as likely to get tornadoes compared to New York City, the damage potential is much higher in the latter as the region is more populated and more properties are at risk, said FEMA officials.

"It's that risk perception that it won't happen to me. Just because I haven't seen it in my lifetime doesn't mean it won't happen," said Grimm. Disaster experts said that people should think about those natural disasters which happened very rarely in the past but affected the maximum number of people—for example, Hurricane Katrina and the 2011 super outbreak of tornadoes.

David Ropeik, a retired Harvard risk communications lecturer and author of How Risky Is It, Really?, said that something like FEMA's new index "opens our eyes to the gaps between what we feel and what is."